Advanced Welding Processes: Technologies and Process Control

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Gas metal arc welding 135 otherwise be rather complex control requirements. It is important to recognize that it is still necessary to choose an appropriate metal transfer technique for a given application; whilst the synergic control techniques improve the ease of use of the equipment, they do not alter the basic features of the transfer mode. Additional improvements in deposition rate may be achieved by DCEN operation, utilizing the resistive heating of the electrode extension or employing multi-wire techniques.
8.1 Introduction Advances in the high-energy processes, high-current plasma, electron beam and laser welding, have been concerned with the application of the technology to the fabrication of engineering materials. The power density of these processes is significantly higher than that of the common arc welding processes [143] and normally above 10 9 W m –2 ; typical values are compared in Fig. 8.1. As a consequence of the high energy concentration, the mechanism of weld pool formation is somewhat different from that normally found in other fusion welding processes. The material in the joint area is heated to very high temperatures and may vaporize, a deep crater or hole is formed immediately under the heat source and a reservoir of molten metal is produced behind this 1.000E+15 1.000E+14 1.000E+13 1.000E+12 1.000E+11 1.000E+10 1.000E+09 1.000E+08 1.000E+07 1.000E+06 1.000E+05 136 Power density (W m –2 ) Vaporisation Vaporisation, conduction melting (keyholes) 8 High-energy density processes Negligible melting Radial conduction with melting GTAW/GM/AW Plasma YAG laser CO 2 laser electron beam process 8.1 Comparative power density of various welding processes. [143, 144]
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Advanced welding processes i
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Advanced welding processes Technolo
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Contents Preface ix Acknowledgement
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Contents vii 10.4 Automated control
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Welding has traditionally been rega
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Acknowledgements I would like to ac
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1.1 Introduction Welding and joinin
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An introduction to welding processe
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Stage 1 Stage 2 An introduction to
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Slag deposit on weld surface An int
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∑ no heavy slag - reduced post-we
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Electro slag SAW multi wire SAW FCA
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Weld metal used (kg m -1 ) 40 35 30
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Advanced process development trends
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% consumed 70 60 50 40 30 20 10 Adv
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Advanced process development trends
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Mains input Power regulation Contro
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Welding power source technology 29
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Three-phase transformer Three-phase
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Mains input Welding power source te
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Off line storage Operator interface
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4.2.1 Improved toughness Filler mat
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Filler materials for arc welding 47
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Flat strip Solidified slag on weld
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Gases for advanced welding processe
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CVN impact energy (J) 200 150 100 5
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∑ argon plus 15-25% carbon dioxid
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25 23 21 19 17 15 13 11 9 7 20 18 1
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Ozone emission (ml min -1 ) 4 3 2 1
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Table 5.3 Continued Argon + 1 to 7%
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Advanced gas tungsten arc welding 7
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Power source Advanced gas tungsten
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Number of arc starts 35 30 25 20 15
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Page 98 and 99: Water cooling 6.7 Dual-shielded GTA
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Page 102 and 103: ∑ low current: 0.1-15 A; ∑ inte
Page 110 and 111: Surface tension Surface tension Adv
Page 114 and 115: 7.2.1 Globular drop transfer Metal
Page 116 and 117: Gas metal arc welding 103 projected
Page 118 and 119: Droplet forming 7.6 Drop spray tran
Page 120 and 121: Number of counts 100 80 60 40 20 0
Page 122 and 123: Metal cored Rutile Basic Self-shiel
Page 124 and 125: F d Fem F v F st F g 7.13 Balance o
Page 126 and 127: Gas metal arc welding 113 is the cu
Page 128 and 129: Stick out Dip transfer Pulse/spray
Page 130 and 131: Gas metal arc welding 117 V = M + A
Page 132 and 133: Voltage (V) 50 40 30 20 10 Gas meta
Page 134 and 135: Pulse current t p 7.23 Pulsed trans
Page 136 and 137: Gas metal arc welding 123 The mean
Page 138 and 139: Wire feed rate (m min -1 ) 11 10.5
Page 140 and 141: Gas metal arc welding 127 Improveme
Page 142 and 143: Gas metal arc welding 129 and a num
Page 144 and 145: Current (A) 500 400 300 200 100 0 G
Page 146 and 147: Pulse amplitude (A) 500 400 300 200
Page 150 and 151: High-energy density processes 137
Page 152 and 153: High-energy density processes 139 P
Page 154 and 155: Arc voltage 30 25 20 15 10 High-ene
Page 156 and 157: High-energy density processes 143 N
Page 158 and 159: Reflecting mirror Laser cavity Powe
Page 160 and 161: High-energy density processes 147 H
Page 162 and 163: Laser beam Gas lens Plasma control
Page 164 and 165: High-energy density processes 151 P
Page 166 and 167: High-energy density processes 153 M
Page 168 and 169: High-energy density processes 155 a
Page 170 and 171: High-energy density processes 157 l
Page 172 and 173: High-energy density processes 159 p
Page 174 and 175: 8.4.5 Practical considerations High
Page 176 and 177: Sliding particle stop Undeflected b
Page 178 and 179: 9.1 Introduction 9 Narrow-gap weldi
Page 180 and 181: 6-16 mm Parallel-sided with backing
Page 182 and 183: Water cooling Main Shielding-gas po
Page 184 and 185: Narrow-gap welding techniques 171 T
Page 186 and 187: 9.7 ‘Twist arc’ narrow-gap GMAW
Page 188 and 189: GMAW torch The NOW process GMAW tor
Page 190 and 191: Narrow-gap welding techniques 177 T
Page 192 and 193: 10.1 Introduction 10 Monitoring and
Page 194 and 195: Monitoring and control of welding p
Page 196 and 197: PROJECT: WELDING CODE : WELDING PRO
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TYPE TOUGHNESS TEST TYPE No. TEMP R
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Monitoring and control of welding p
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Data RAM ADC I/O device Monitoring
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Current I(A) 150 140 130 120 110 Mo
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Table 10.5 Stability criteria Monit
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CCD camera Travel direction Torch M
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Welding automation and robotics 219
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Table 11.1 Robot applications Weldi
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∑ evaluate alternatives; ∑ eval
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Option Manual metal arc Gas metal a
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Appendices Appendices 247
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Arc Metal arc Manual metal arc Resi
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Tensile strength Appendices 251 Des
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Appendices 253 Exx16 Basic low-hydr
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GMAW stainless steel c Wire feed sp
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Appendix 4 American, Australian and
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Appendices 259 Carbon Manganese ste
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Consumable type Features Applicatio
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Appendix 7 Plasma keyhole welding o
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References [1] British Standards In
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References 267 [40] Anon, 1989 ‘S
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References 269 [88] Boughton P and
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References 271 Century Conference (
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References 273 [178] Benn B, 1988
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References 275 [224] Philpott M L,
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References 277 [269] UK Patent 8411
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Activated TIG (A-TIG) 91, 97 adapti
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digital measuring systems 189-90 di
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high-frequency high-voltage arc ini
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current measurement 194-6 determina
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carbon dioxide 63-4, 64-6 chlorine
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Advanced Welding Processes: Technologies and Process Control

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